The present invention relates to a focal plane shutter for a digital camera.
Some of focal plane shutters for a digital camera include two shutter blades called a first blade and a second blade. In this type of focal plane shutter, usually, a first blade and a second blade are coupled to a driving member for a first blade and a driving member for a second blade similarly to a focal plane shutter for a camera using a film. Thus, in a setting state in a photographing standby state, the first blade covers an exposure opening, and the second blade withdraws from the exposure opening. When photographing is performed, the two driving members are rotated in order in the same direction by the urging force of a driving spring for a first blade and the urging force of a driving spring for a second blade, the first blade opens the exposure opening, and the second blade closes afterward so as to expose an imaging surface of an imaging device. Therefore, it is common that a digital camera including the focal plane shutter of such a configuration has an optical view finder (hereinafter referred to as an optical finder).
Additionally, in the focal plane shutter for a digital camera of such a configuration, if the second blade fully closes the exposure opening, imaging information is stored in a storage device via an information processing circuit from the imaging device, and a setting operation is performed immediately. However, in the setting operation, a setting member rotated from an initial position reverses two driving members thereof to a setting position against the urging force of each driving spring. As a configuration for maintaining the two driving members in the setting state until the next photographing is performed, focal plane shutters called a locking type and a direct type are known.
That is, in the focal plane shutter called the locking type, the two driving members are locked by locking members until the first blade and the second blade are made to perform an exposure operation when photographing is performed. Therefore, the setting member can be adapted to be immediately returned to an initial position if the two driving members can be locked by the respective locking members at setting positions by the setting operation. However, at the time of the release of the camera, the setting member can also be adapted so as to be returned to the initial position prior to the opening operation of the first blade. The exposure operation of the first blade and the second blade is performed as two release means whose operation is allowed in order by the respective electromagnets release the lock of the respective driving members by the respective locking members.
In contrast, in the focal plane shutter called the direct type, the two driving members include iron piece members, respectively, and the setting member rotates the two driving members against the urging forces of the respective driving springs until the iron piece members thereof come into contact with respective electromagnets which are not yet magnetized by the setting operation. Therefore, the setting member is not immediately returned to the initial position, and maintains the state even after that, and the setting member is returned to the initial position if the respective electromagnets are magnetized and the iron piece members thereof are attracted and held by magnetic attractive forces, at the time of the release of the camera. After that, the exposure operation of the first blade and the second blade is performed as the respective electromagnets are demagnetized in order and the attractive holding forces of the respective iron piece members are lost.
Although the invention relates to the locking type focal plane shutter for a digital camera including the first blade and the second blade in the above shutters, JP-A-2001-305605 discloses such a locking type focal plane shutter for a camera which can be adopted not only for a digital camera but also for a camera using a film.
Among the focal plane shutters for a digital camera including the first blade and the second blade, there is one that performs photographing by using an electronic view monitor (hereinafter referred to as a monitor) including display panels, such as a liquid crystal display panel or an EL (electroluminescence) display panel, instead of the optical finder though not the locking type described in JP-A-2001-305605. Additionally, in that case, it is known that an imaging device for photographing is made to be used also as an imaging device for a monitor. An example of focal plane shutters for a digital camera which allows such a configuration to be realized is described in JP-A-2004-37590.
In the focal plane shutter described in JP-A-2004-317590, both a first blade and a second blade are brought into a state where the blades have withdrawn from an exposure opening in a photographing standby state. If a release button is pushed when photographing is performed, in the initial stage, operation is made in a state where the first blade has covered the exposure opening. In the next stage, if the release button is pushed when performing photographing, in addition to photographing in a mode in which the first blade and the second blade are made to perform an exposure operation, photographing in a mode in which an electronic control circuit controls an imaging device to start photographing, and the second blade closes the exposure opening to end photographing, or photographing in a mode in which the electronic control circuit is adapted to control both the start and end of photographing can be performed without operating the first blade. Moreover, while the release button is pushed, an electronic control circuit repeats a predetermined operation so that the photographing of a moving image can be performed.